Developments in the mineral oil sector and in the steel industry have resulted recently in efforts to utilize water-cooled combination electrodes for industrial arc electrode processes.
Compared to uncooled electrodes, one important advantage offered by a water-cooled electrode is a reduction in the consumption of electrode graphite during operation, an attractive improvement for electric steel works, resulting both from recent excessive increases in price of raw materials making desirable a reduction of steel production costs in general, and rising energy costs making desirable any savings in energy consumption.
Prior developments in this field are set forth in detail in European Patent Specifications Nos. 50682, 50683 and 51074 (U.S. Pat. Nos. 4,468,783, 4,425,657, and 4,466,105), but still leave room for desirable further developmental efforts. European Patent Specifications Nos. 50682, 50683 and 51074 describe combination electrodes which include a water cooled metallic electrode holder surrounded by temperature resistant rings protecting the electrode holder against the furnace atmosphere. A consumable section of graphite is threadably connected to the lower end of the electrode holder by means of a threaded nipple. A lower front plate of the electrode holder is covered by an upper, front face of the consumable section and is therefore not exposed to hazardous furnace environmental conditions or attack by an electric arc strike during normal arc furnace operation.
Where the furnace is operated in an inappropriate manner or where scrap material is very heavy, the consumable sections may occasionally break. In the event of breakage, the unprotected lower front plate of the electric holder may be exposed to elevated temperature and to an electric arc, which exposure may lead to a damage of the metal section.